This application relates generally to magnetic disc drives and more particularly to a load/unload ramp for use in a disc drive.
Disc drives are data storage devices that store digital data in magnetic form on a rotating storage medium on an information storage disc. Modern disc drives comprise one or more rigid information storage discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (xe2x80x9cheadsxe2x80x9d) mounted to a radial actuator for movement of the heads in an arc across the surface of the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The recording transducer, e.g. a magnetoresistive read/write head, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the head senses the data previously written on the disc track and transfers the information to a host computing system. The overall capacity of the disc drive to store information is dependent upon the disc drive recording density.
The transducers are mounted on sliders or heads via flexures at the ends of a plurality of actuator arms that project radially outward from the actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the transducers move in a plane parallel with the surfaces of the discs.
Typically, such rotary actuators employ a voice coil motor to position the transducers with respect to the disc surfaces. The actuator voice coil motor includes a coil mounted on the side of the actuator body opposite the transducer arms so as to be immersed in the magnetic field of a magnetic circuit comprising one or more permanent magnets and magnetically permeable pole pieces. When controlled direct current (DC) is passed through the coil, an electromagnetic field is set up which interacts with the magnetic field of the magnetic circuit to cause the coil to move in accordance with the well-known Lorentz relationship. As the coil moves, the actuator body pivots about the pivot shaft and the transducers move across the disc surfaces. The actuator thus allows the transducer to move back and forth in an arcuate fashion between an inner radius and an outer radius of the discs.
When a stop-start contact disc drive is de-energized, the transducers are automatically moved to a storage location or xe2x80x9cparkxe2x80x9d location on the disc surfaces. The park location is typically adjacent and outside the inner or outer periphery of the data storage region of the disc and is typically called a landing zone. This landing zone typically does not contain any useable data as the transducer physically contacts the disc at rest. Consequently, any data stored in this area would likely be lost or compromised. In addition, the landing zone is typically roughened to minimize the stiction of the transducer against the disc surface.
Other disc drives utilize load/unload ramps to facilitate the removal of the transducer away from the disc to a parked position adjacent the disc. The load/unload ramp in a disc drive is typically stationary and located at a peripheral portion of the information storage disc. Removal of the transducer from the disc media is accomplished by the transducer/suspension assembly moving to the outer rim portion of the disc and then traversing an inclined portion of the load/unload ramp to a park location on a flat portion of the load/unload ramp. As such, the transducer is physically xe2x80x9cparkedxe2x80x9d off of the information storage disc surface.
The use of a load/unload ramp to store the transducer under de-energized conditions has several advantages over the use of the traditional landing zone design where the transducer is stored on the disc surface. First, using a load/unload ramp eliminates stiction concerns and friction failures associated with the transducer being de-energized on the landing zone of the disc. Second, information storage discs typically have a protective carbon overcoat which at least in part is required to support the transducer-landing zone interaction. In the absence of this interaction, a thinner carbon overcoat may be utilized on the disc surface. A thinner carbon overcoat on the information storage disc allows for the design of decreased transducer-to-disc media spacing and for a corresponding increase in recording density. Finally, by parking the transducer head off the information storage disc surface on the load/unload ramp, a larger amount of disc space is available for data storage, which also results in an increased recording density.
However, the use of a load/unload ramp in a disc drive has several disadvantages, one of which is that the numerous interactions between the transducer/suspension assembly and the load/unload ramp causes wear and resultant debris formation on the surface of the load/unload ramp. Debris formation inside the disc drive is a major concern in the disc drive industry as it can lead to disc errors and ultimately disc failure. Thus, minimizing friction and wear between the load/unload ramp and the transducer/suspension assembly is a major concern in the disc drive art.
Against this backdrop various embodiments of the present invention have been developed. One embodiment is a gamma irradiated load/unload ramp and method for preparing a gamma irradiated load/unload ramp for use in a disc drive. The gamma irradiated load/unload ramp has improved wear resistance properties over prior art load/unload ramps and hence show a decreased propensity to form wear debris during normal disc drive operations. The load/unload ramp is made by forming the load/unload ramp preferably from a liquid crystal polymer, placing the ramp in a gamma-field, and irradiating the ramp in an amount sufficient to harden the ramp.
The load/unload ramp is preferably utilized in a disc drive having an information storage disc rotatably mounted on a spin motor where the spin motor is fastened to a base plate. The disc drive includes an actuator assembly for directing a transducer over a surface of the information storage disc, and a hardened load/unload ramp having an absorbed radiation dose of about 0.05 to 0.5 Mrads. The load/unload ramp is positioned adjacent a peripheral portion of the information storage disc for supporting the transducer when the transducer is rotated off of the information storage disc.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.